Head Cooling in Ischaemic Stroke Patients Undergoing Endovascular Thrombectomy (COOLHEAD-2b)

Final infarct volume (mL), defined as the manually segmented volume of infarcted brain tissue on 24-hour follow-up CT or MRI brain imaging. Segmentation will be performed by a blinded imaging core laboratory using de-identified imaging files.

Infarct growth, defined as the difference between the final infarct volume on 24-hour follow-up imaging and the baseline infarct core volume estimated using automated CT perfusion software (relative cerebral blood flow <30%).

Penumbral salvage index, defined as the proportion of baseline hypoperfused or penumbral brain tissue not progressing to infarction, calculated using baseline CT perfusion imaging and final infarct volume on 24-hour follow-up imaging.

Early neurological improvement, defined as the percentage change in the National Institutes of Health Stroke Scale (NIHSS), a neurological deficit scale ranging from 0 to 42 where higher scores indicate worse neurological impairment, from baseline to 24 hours

Degree of disability or dependence in daily activities measured using the modified Rankin Scale (mRS), an ordinal scale ranging from 0 (no symptoms) to 6 (death), where higher scores indicate greater disability. Assessment is performed by a trained, blinded study team member using the Rankin Focused Assessment.

Proportion of participants achieving functional independence, defined as a modified Rankin Scale (mRS) score of 0 to 2, where lower scores indicate less disability.

Proportion of participants achieving an excellent functional outcome defined as a modified Rankin Scale (mRS) score of 0 to 1, where lower scores indicate minimal or no disability.

Number of days participants are alive and not admitted to hospital during the first 90 days after endovascular thrombectomy.

Death from any cause.

Symptomatic intracranial haemorrhage defined according to the Safe Implementation of Thrombolysis in Stroke-Monitoring Study (SITS-MOST) criteria as a parenchymal haemorrhage type 2 associated with neurological deterioration (increase in NIHSS score ≥4 points) or death.

Occurrence of a new cardiac arrhythmia associated with haemodynamic instability requiring clinical intervention.

Blood pressure >185/110 mmHg or an absolute increase in systolic blood pressure ≥30 mmHg from baseline on two consecutive measurements despite standard pharmacological treatment.

Clinically significant shivering attributed to head cooling that persists despite systemic warming measures.

Pneumonia diagnosed according to Centers for Disease Control and Prevention criteria.

Any local skin injury attributed to pressure or cold exposure from the head cooling device.

Angiographic vasospasm occurring during endovascular thrombectomy requiring administration of intra-arterial vasodilators.

Composite outcome including target vessel dissection, vessel perforation, intracranial haemorrhage, or access site haematoma occurring during or immediately following the EVT procedure.